Learn Astrophysics — Artemis II Mission

Orbiting Is Falling

The only difference between a ball dropping
and a spacecraft orbiting is speed.

2,000 m/s
Choose a speed, then launch. Try increasing it gradually.

What you're seeing

You're on top of a mountain, launching a projectile forward. Gravity pulls it down. At low speeds it arcs and hits the ground — exactly what you'd expect.

But increase the speed and the arc gets longer. The projectile travels so far that something changes: the Earth curves away beneath it. The ground is dropping as fast as the projectile is falling.

At about 7,800 m/s, the projectile never lands. It keeps falling, and keeps missing. The trail wraps all the way around and connects with itself.

That's an orbit. It's not floating. It's not weightless because gravity stopped. It's falling — permanently — with the ground forever curving away.

Artemis II right now: The Orion capsule and its four crew are falling. They've been falling since their engines cut off two days ago. They'll keep falling all the way to the Moon and back. Everything in space falls. The only question is: how fast, and in what direction?
Part 1 — Orbiting Part 2: The Journey →